Field of the Invention
This invention relates to medical devices for assisting natural organs in providing blood flow.
The failure of the heart to provide sufficient blood flow is a seriously debilitating problem with symptoms ranging from shortness of breath or swollen limbs to total confinement in bed. In extreme cases, it can result in death. While some forms of heart disease have declined and have been controlled through other therapies, heart failure is a growing problem.
The more serious cases of heart failure have been treated by total replacement of the heart. Transplants of human hearts have saved some patients threatened with death from heart failure. Of course, a heart transplant is a drastic operation with considerable risk. Also, the supply of donor hearts is very limited and cannot meet demand.
Much research has been done in attempting to develop an artificial heart that can replace the human heart in such serious cases. Currently, the artificial heart is in use as a temporary pump pending the location of a human heart for transplant.
A less intrusive method of providing sufficient blood flow is to assist the patient's heart in its pumping process. In this way, there is no risk of rejection and other problems that accompany a heart transplant. Various assist methods have been tried. One train of research has used transformed skeletal muscle to provide the power for the assist. For example, Dr. Ray C.-J. Chiu's book entitled Biomechanical Cardiac Assist illustrates a bypass in the aorta. To this bypass is attached a pouch surrounded by skeletal tissue. The skeletal tissue is stimulated by an electrical implantable tissue stimulator. The heart's beating is sensed and the properly conditioned skeletal muscle is pulsed to help in moving blood through the aorta. Considerable research has been done in determining proper muscle choice, such as latissimus dorsi, to use in such an assist.
Another train of development involves the use of mechanical pumps for moving blood. For example, the Biomedicus pump has been used for moving blood through the patient.
One drawback of these continuous power sources is that they lack pulsatility. In the literature, it is urged that a pulsatile system provides a more physiologic flow of blood.
What is needed is a system with a pumping configuration powerful enough to provide sufficient blood flow, while also providing the pulsatility which is believed necessary for the proper end organ perfusion.